Battery monomer and preparation method thereof, battery and power utilization device

Abstract

The invention provides a battery monomer and a preparation method thereof, a battery and a power utilization device, and belongs to the technical field of batteries. The battery monomer comprises a negative pole piece and an electrolyte, and the electrolyte comprises a solid electrolyte and a liquid electrolyte. The ratio of the fully-charged thickness of the negative pole piece to the uncharged thickness of the negative pole piece is x, and the ratio of the mass of the solid electrolyte in the electrolyte to the mass of the electrolyte is y. When x is less than or equal to 20%, 0 < y < = 50%. And when x is more than 20% and less than 80%, y is more than 50% and less than 90%. When x > = 80%, 90% < = y < = 96%. According to the battery monomer, the liquid electrolyte and the solid electrolyte are matched, and the ratio of the mass of the solid electrolyte to the mass of the electrolyte in the battery monomer with the negative pole pieces with different volume expansion rates is limited, so that extrusion of the liquid electrolyte can be reduced or avoided, and the electrolyte can also provide a relatively good lithium ion transmission rate; and the battery monomer can take both cycle performance and capacity performance into account.

Description

Battery monomer and preparation method thereof, battery and power-using device Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] With the development of lithium-ion batteries, the industry and market have higher energy density demands. Silicon and lithium metal offer exceptionally high theoretical specific capacities as anode materials, but their volume expansion poses significant challenges to their application. Batteries using silicon and lithium metal as anode materials experience continuous expansion and contraction during cycling, exacerbating the dissipation of liquid electrolyte, preventing it from recirculating and causing a drop in battery cycle performance.

[0003] Summary of the Invention

[0004] In view of the above problems, the present application provides a battery cell and a preparation method thereof, a battery and an electrical device, which can enable the battery to have both cycle performance and capacity performance.

[0005] In a first aspect, the present application provides a battery cell comprising: a negative electrode plate and an electrolyte, wherein the electrolyte comprises a solid electrolyte and a liquid electrolyte. The ratio of the thickness of the fully charged negative electrode plate to the thickness of the uncharged negative electrode plate is x, and the ratio of the mass of the solid electrolyte in the electrolyte to the mass of the electrolyte is y. When x ≤ 20%, 0 < y ≤ 50%. When 20% < x < 80%, 50% < y < 90%. When x ≥ 80%, 90% ≤ y ≤ 96%.

[0006] In the technical solution of the embodiment of the present application, the battery cell of the present application is combined with a liquid electrolyte and a solid electrolyte, and the ratio of the mass of the solid electrolyte to the mass of the electrolyte in the battery cell with negative electrode plates having different volume expansion rates is limited. This can not only reduce or avoid the extrusion of the liquid electrolyte, but the electrolyte can also provide a better lithium ion transmission rate, so that the battery cell can take into account both cycle performance and capacity performance.

[0007] In some embodiments, when x≤20%, 0<y≤10%. When 20%<x<80%, 70%≤y<90%. When x≥80%, 90%≤y≤93%. When x≤20%, the volume expansion rate of the negative electrode plate is low, and 0<y≤10% can enable the battery cell to obtain both a higher number of cycles and a larger battery capacity; when 20%<x<80%, 70%≤y<90%, the volume expansion rate of the negative electrode plate is average, and 70%≤y<90% can enable the battery cell to take into account both the number of cycles and the battery capacity; when x≥80%, the volume expansion rate of the negative electrode plate is large, and 90%≤y≤93% can enable the battery cell to obtain a higher number of cycles and take into account the battery capacity.

[0008] In some embodiments, the solid electrolyte is a heat-curable electrolyte, which can be cured under heating conditions to form a solid electrolyte.

[0009] In some embodiments, the curing temperature of the heat-curable electrolyte is 50° C. to 110° C. The curing temperature of the heat-curable electrolyte is relatively low and is within the safe operating temperature range of the battery cell.

[0010] In some embodiments, the liquid electrolyte includes a lithium salt and / or a sodium salt, and the lithium salt includes any one or more of LiPF6, LiClO4, LiTFSI, LiFSI, LiBOB, LiDFOB, and LiNO3.

[0011] In a second aspect, the present application provides a method for preparing a battery cell according to the above-described embodiment, comprising: preparing an electrode assembly, placing the electrode assembly in a housing, injecting a raw material for forming a solid electrolyte into the housing, solidifying the raw material for the solid electrolyte to form a solid electrolyte, and continuously injecting a liquid electrolyte into the housing containing the electrode assembly, and sealing the housing.

[0012] In the technical solution of the embodiment of the present application, the preparation method of the battery cell of the present application is to first inject the raw materials for forming the solid electrolyte into the shell containing the electrode assembly, and after the raw materials for the solid electrolyte are solidified to form the solid electrolyte, the liquid electrolyte is injected into the shell containing the electrode assembly, so as to obtain a mixed electrolyte including the solid electrolyte and the liquid electrolyte, that is, the mixing of the solid electrolyte and the liquid electrolyte is achieved by only two liquid injections, which simplifies the preparation process of the battery cell and reduces the process cost of the battery cell.

[0013] In some embodiments, the solid electrolyte is a heat-curable electrolyte. After injecting raw materials for the heat-curable electrolyte into a housing containing the electrode assembly, the raw materials are allowed to react at 50°C to 110°C for 3 to 24 hours to form a solid electrolyte. The curing process of the heat-curable electrolyte of the present application is simple and can form a stable solid electrolyte.

[0014] In some embodiments, the raw materials of the heat-curable electrolyte include a liquid electrolyte, a polymerizable monomer, and an initiator. Under heating conditions, the polymerizable monomer can polymerize under the action of the initiator to form a polymer, and the polymer absorbs part of the liquid electrolyte to form a solid electrolyte.

[0015] In some embodiments, the mass fraction of the polymerizable monomer in the raw material is 0.5 wt% to 6.5 wt%. When the mass fraction of the polymerizable monomer in the raw material is 0.5 wt% to 6.5 wt%, the polymerizable monomer can be polymerized under the action of the initiator to form a high polymer, which absorbs part of the liquid electrolyte to form a solid electrolyte, thereby obtaining an electrolyte composed of a liquid electrolyte and a solid electrolyte.

[0016] In some embodiments, the mass fraction of the initiator in the raw materials is 0.1 wt% to 0.5 wt%. When the mass fraction of the initiator in the raw materials is 0.1 wt% to 0.5 wt%, the monomers can polymerize under the action of the initiator to form a polymer, and the polymer absorbs part of the liquid electrolyte to form a solid electrolyte, thereby obtaining an electrolyte composed of a liquid electrolyte and a solid electrolyte.

[0017] In some embodiments, the polymerizable monomer has an unsaturated double bond. The polymerizable monomer having an unsaturated double bond can be polymerized to form a high polymer under the action of an initiator, and the high polymer absorbs part of the liquid electrolyte to form a solid electrolyte.

[0018] In some embodiments, the polymerizable monomers include any one or more of ester monomers, carbonate monomers, sulfone monomers, isocyanates, amide monomers, nitrile monomers, and fluorinated monomers. These monomers can be polymerized under the action of an initiator to form a high polymer, which absorbs a portion of the liquid electrolyte to form a solid electrolyte.

[0019] In some embodiments, the initiator includes any one or more of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, azoisobutylcyanamide, azobiscyclohexylcarbonitrile, dimethyl azobisisobutyrate, azobisisobutylamidine hydrochloride, azobisisopropylimidazoline hydrochloride, and azobiscyanovaleric acid. The above initiators can initiate polymerization of the monomers to form a polymer, which absorbs part of the liquid electrolyte to form a solid electrolyte.

[0020] In a third aspect, the present application provides a battery comprising the battery cell in the above embodiment.

[0021] In a fourth aspect, the present application provides an electrical device, which includes the battery cell or battery in the above embodiment, and the battery cell or battery is used to provide electrical energy.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0024] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application;

[0025] FIG2 is a schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0026] FIG3 is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application.

[0027] The accompanying drawings in the specific implementation manner are as follows:

[0028] 1000-Vehicle; 100-Battery; 200-Controller; 300-Motor;

[0029] 10- box body; 11- first part; 12- second part;

[0030] 20 - battery cell; 21 - end cap; 22 - housing; 23 - electrode assembly. DETAILED DESCRIPTION

[0031] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0033] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0034] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0036] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0037] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0038] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0039] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0040] With the development of lithium-ion batteries, the industry and market have higher energy density demands. Silicon and lithium metal offer exceptionally high theoretical specific capacities as anode materials, but their volume expansion poses significant challenges to their application. Batteries using silicon and lithium metal as anode materials experience continuous expansion and contraction during cycling, exacerbating the dissipation of liquid electrolyte, preventing it from recirculating and causing a drop in battery cycle performance.

[0041] Solid-state electrolytes generally offer superior thermodynamic and electrochemical stability, as well as mechanical strength, compared to liquid electrolytes. They also offer more stable ion conduction and ion deposition, enabling more stable cycling of lithium-ion batteries. Solid-state electrolytes also act as liquid locks, preventing liquid electrolyte extrusion in high-expansion systems. Liquid electrolytes offer high ionic conductivity and excellent recirculation and wetting in batteries, but they also offer lower safety.

[0042] Based on the above considerations, in order to improve the performance of battery cells, the present application comprehensively utilizes the advantages of solid electrolytes and liquid electrolytes, combines liquid electrolytes and solid electrolytes, and limits the ratio of the mass of solid electrolyte to the mass of electrolyte in battery cells with negative electrode plates with different volume expansion rates. This can not only reduce or avoid the extrusion of liquid electrolytes, but the electrolyte can also provide a better lithium ion transmission rate, so that the battery cells can take into account both cycle performance and capacity performance.

[0043] The battery referred to in the embodiments of this application refers to a single physical module that includes multiple battery cells to provide higher voltage and capacity. The battery generally includes a battery box for enclosing multiple battery cells. The battery box can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0044] Each battery cell is a secondary battery; it can be a lithium-ion battery or a lithium-sulfur battery, but is not limited to these. Battery cells can be cylindrical, flat, rectangular, or other shapes. Battery cells are generally categorized into three types based on packaging: cylindrical, prismatic, and pouch-type.

[0045] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The uncoated positive electrode collector protrudes from the coated positive electrode collector. This serves as the positive electrode tab. For lithium-ion batteries, for example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The uncoated negative electrode collector protrudes from the coated negative electrode collector. This serves as the negative electrode tab. The negative electrode current collector can be made of copper. To ensure that high currents can pass without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together. The separator can be made of polypropylene (PP) or polyethylene (PE). In addition, the electrode assembly can be a wound structure or a laminated structure, but the embodiments of the present application are not limited to this.

[0046] The battery cell also includes a current collecting component, which is used to electrically connect the tabs and electrode terminals of the battery cell to transmit electrical energy from the electrode assembly to the electrode terminals, and then to the outside of the battery cell through the electrode terminals; multiple battery cells are electrically connected through the current collecting component to realize series, parallel or mixed connection of multiple battery cells.

[0047] The battery also includes sampling terminals and a battery management system. The sampling terminals are connected to the busbar and are used to collect information about the battery cells, such as voltage or temperature. The sampling terminals transmit the collected battery cell information to the battery management system. If the battery management system detects that the battery cell information is outside the normal range, it will limit the battery's output power for safety protection.

[0048] It will be appreciated that the electrical devices applicable to the batteries described in the embodiments of the present application may be in various forms, for example, mobile phones, portable devices, laptop computers, electric vehicles, electric cars, ships, spacecraft, electric toys and electric tools, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc. Electric toys include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting power tools, grinding power tools, assembly power tools and railway power tools, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.

[0049] The battery cells and batteries described in the embodiments of the present application are not limited to the electrical devices described above, but can also be applied to all electrical devices using battery cells and batteries. However, for the sake of simplicity, the following embodiments are described using electric vehicles as an example.

[0050] Please refer to Figure 1, which is a structural diagram of a vehicle provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0051] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0052] Please refer to Figure 2, which is an exploded view of a battery provided in some embodiments of the present application. Battery 100 includes a housing 10 and battery cells 20, with battery cells 20 housed within housing 10. Housing 10 provides storage space for battery cells 20 and can have various structures. In some embodiments, housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for battery cells 20. Second portion 12 can be a hollow structure with one end open. First portion 11 can be a plate-like structure, with first portion 11 overlapping the open side of second portion 12, so that the first and second portions 11 and 12 together define a storage space. Alternatively, first portion 11 and second portion 12 can each be a hollow structure with one end open, with the open side of first portion 11 overlapping the open side of second portion 12. Housing 10 formed by first portion 11 and second portion 12 can have various shapes, such as a cylinder or a rectangular parallelepiped.

[0053] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0054] Each battery cell 20 is a secondary battery, which may be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0055] Please refer to Figure 3, which is a schematic diagram of the exploded structure of a first type of battery cell provided in some embodiments of the present application. A battery cell 20 is the smallest unit that makes up a battery. As shown in Figure 3, a battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0056] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the housing 22 to match the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, allowing the battery cell 20 to have higher structural strength and improved safety. Functional components such as electrode terminals can be provided on the end cap 21. The electrode terminals can be used to electrically connect to the electrode assembly 23 for outputting or inputting electrical energy into or out of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application are not particularly limited in this regard. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0057] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0058] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0059] According to some embodiments of the present application, a battery cell is provided, comprising: a negative electrode plate and an electrolyte, wherein the electrolyte comprises a solid electrolyte and a liquid electrolyte. The ratio of the thickness of the fully charged negative electrode plate to the thickness of the uncharged negative electrode plate is x, and the ratio of the mass of the solid electrolyte in the electrolyte to the mass of the electrolyte is y. When x ≤ 20%, 0 < y ≤ 50%. When 20% < x < 80%, 50% < y < 90%. When x ≥ 80%, 90% ≤ y ≤ 96%.

[0060] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0061] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0062] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0063] In some embodiments, the negative electrode active material may adopt a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0064] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0065] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0066] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0067] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0068] The electrolyte conducts ions between the positive and negative electrodes.

[0069] The full charge thickness of the negative electrode plate is the thickness of the negative electrode plate after the battery cell is fully charged.

[0070] The uncharged thickness of the negative electrode plate is the thickness of the negative electrode plate after cold pressing and before charging.

[0071] The mass of the electrolyte is the sum of the mass of the solid electrolyte and the mass of the liquid electrolyte.

[0072] As an example, when x≤20%, the value of y can be 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48% or 50%.

[0073] When 20%<x<80%, the value of y can be 51%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88% or 89%.

[0074] When x ≥ 80%, the value of y may be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%.

[0075] The battery cell of the present application is a combination of liquid electrolyte and solid electrolyte, and limits the ratio of the mass of the solid electrolyte to the mass of the electrolyte in the battery cell with negative electrode plates of different volume expansion rates. This can not only reduce or avoid the extrusion of the liquid electrolyte, but also the electrolyte can provide a better lithium ion transmission rate, so that the battery cell can take into account both cycle performance and capacity performance.

[0076] According to some embodiments of the present application, optionally, when x≤20%, 0<y≤10%. When 20%<x<80%, 70%≤y<90%. When x≥80%, 90%≤y≤93%.

[0077] When x≤20%, the volume expansion rate of the negative electrode plate is low, and 0<y≤10% can enable the battery cell to obtain both a higher number of cycles and a larger battery capacity; when 20%<x<80%, 70%≤y<90%, the volume expansion rate of the negative electrode plate is average, and 70%≤y<90% can enable the battery cell to take into account both the number of cycles and the battery capacity; when x≥80%, the volume expansion rate of the negative electrode plate is large, and 90%≤y≤93% can enable the battery cell to obtain a higher number of cycles and take into account the battery capacity.

[0078] According to some embodiments of the present application, optionally, the solid electrolyte is a heat-curable electrolyte.

[0079] The heat-curable electrolyte can be cured under heating conditions to form a solid electrolyte.

[0080] According to some embodiments of the present application, optionally, the curing temperature of the heat-curable electrolyte is 50° C. to 110° C.

[0081] As an example, the curing temperature of the heat-curable electrolyte may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, or 110°C.

[0082] The curing temperature of the heat-curable electrolyte is low and within the safe operating temperature range of the battery cell.

[0083] Optionally, the curing temperature of the heat-curable electrolyte is 60°C to 70°C.

[0084] According to some embodiments of the present application, optionally, the liquid electrolyte includes a lithium salt and / or a sodium salt, and the lithium salt includes any one or more of LiPF6, LiClO4, LiTFSI, LiFSI, LiBOB, LiDFOB and LiNO3.

[0085] Optionally, the molar concentration of the lithium salt is 0.9 mol / L to 1.5 mol / L.

[0086] According to some embodiments of the present application, the present application also provides a method for preparing a battery cell of the above-mentioned embodiment, which includes: preparing an electrode assembly, placing the electrode assembly into a shell, injecting raw materials for forming a solid electrolyte into the shell, solidifying the raw materials for the solid electrolyte to form a solid electrolyte, and continuing to inject liquid electrolyte into the shell containing the electrode assembly, and sealing.

[0087] The preparation method of the battery cell of the present application is to first inject the raw materials for forming the solid electrolyte into the shell containing the electrode assembly, and after the raw materials for forming the solid electrolyte are solidified to form the solid electrolyte, the liquid electrolyte is injected into the shell containing the electrode assembly. A mixed electrolyte including the solid electrolyte and the liquid electrolyte can be obtained, that is, the mixing of the solid electrolyte and the liquid electrolyte is achieved by only two injections, which simplifies the preparation process of the battery cell and reduces the process cost of the battery cell.

[0088] Specifically, the method for preparing the battery cell of the present application includes the following steps:

[0089] S1: Assemble the positive electrode sheet, negative electrode sheet and separator together and wind them into a core to obtain a battery cell;

[0090] S2: The battery cell is placed into the shell to complete the packaging, forming a hard shell battery cell without liquid injection;

[0091] S3: Inject the raw materials for forming the solid electrolyte into the battery cell, without plugging the injection port with a sealing nail, and allow it to solidify open;

[0092] S4: Remove the sealing pins, inject the liquid electrolyte into the battery cell, weld the sealing pins, and make a battery cell.

[0093] According to some embodiments of the present application, optionally, the solid electrolyte is a heat-curable electrolyte. After the raw materials of the heat-curable electrolyte are injected into the shell containing the electrode assembly, the raw materials of the heat-curable electrolyte are allowed to react at 50°C to 110°C for 3h to 24h to form a solid electrolyte.

[0094] As an example, the curing time of the heat-curable electrolyte may be 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours, or 24 hours.

[0095] The curing process of the heat-curable electrolyte of the present application is simple and can form a stable solid electrolyte.

[0096] According to some embodiments of the present application, optionally, the raw materials of the heat-curable electrolyte include a liquid electrolyte, a polymerizable monomer, and an initiator.

[0097] Under heating conditions, the polymerizable monomers can be polymerized to form polymers under the action of an initiator, and the polymers absorb part of the liquid electrolyte to form a solid electrolyte.

[0098] According to some embodiments of the present application, optionally, in the raw material, the mass fraction of the polymerization monomer is 0.5 wt% to 6.5 wt%.

[0099] As an example, the mass fraction of the polymerized monomer can be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt% or 6.5 wt%.

[0100] When the mass fraction of the polymerizable monomer in the raw material is 0.5wt% to 6.5wt%, the polymerizable monomer can be polymerized to form a polymer under the action of the initiator, and the polymer absorbs part of the liquid electrolyte to form a solid electrolyte, thereby obtaining an electrolyte composed of a liquid electrolyte and a solid electrolyte.

[0101] According to some embodiments of the present application, optionally, in the raw materials, the mass fraction of the initiator is 0.1 wt% to 0.5 wt%.

[0102] As an example, the mass fraction of the initiator may be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt% or 0.5 wt%.

[0103] When the mass fraction of the initiator in the raw material is 0.1wt% to 0.5wt%, the polymerization monomer can be polymerized to form a polymer under the action of the initiator, and the polymer absorbs part of the liquid electrolyte to form a solid electrolyte, thereby obtaining an electrolyte composed of a liquid electrolyte and a solid electrolyte.

[0104] According to some embodiments of the present application, optionally, the polymerized monomer has an unsaturated double bond.

[0105] The polymer monomer with unsaturated double bonds can be polymerized to form a polymer under the action of an initiator, and the polymer absorbs part of the liquid electrolyte to form a solid electrolyte.

[0106] According to some embodiments of the present application, optionally, the polymerizable monomers include any one or more of ester monomers, carbonate monomers, sulfone monomers, isocyanates, amide monomers, nitrile monomers and fluorinated monomers.

[0107] The above-mentioned polymerizable monomers can be polymerized to form high polymers under the action of an initiator, and the high polymers absorb part of the liquid electrolyte to form a solid electrolyte.

[0108] Optionally, the polymerizable monomer includes one or two of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, polyethylene glycol dimethacrylate, methylene succinic acid, maleic anhydride, acrylamide glycolic acid methyl ether, 2-methacryloyl isocyanate oxyethyl ester, N,N'bisacryloylcystamine, N,N-methylenebisacrylamide, triallyl isocyanurate and ethylene glycol dimethacrylate.

[0109] According to some embodiments of the present application, optionally, the initiator includes any one or more of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, azoisobutylcyanamide, azobiscyclohexylcarbonitrile, dimethyl azobisisobutyrate, azobisisobutyramidine hydrochloride, azobisisopropylimidazoline hydrochloride and azobiscyanovaleric acid.

[0110] The initiator can initiate polymerization of the monomers to form a high polymer, and the high polymer absorbs part of the liquid electrolyte to form a solid electrolyte.

[0111] The following is a further detailed description of a battery cell and its preparation method, a battery and an electrical device of the present application in conjunction with embodiments.

[0112] The parameters of the battery cells of Examples 1 to 15 and Comparative Examples 1 to 10 of the present application are shown in Table 1.

[0113] Table 1 Parameters of battery cells of Examples 1 to 15 and Comparative Examples 1 to 10

[0114] The negative electrode silicon content is the mass percentage of the silicon-based material in the negative electrode active material layer. For example, in Example 7, the negative electrode silicon content = the mass of the silicon oxide compound / (the mass of the artificial graphite + the mass of the silicon oxide compound).

[0115] The preparation method of the battery cells of Examples 1 to 15 and Comparative Examples 1 to 10 is as follows:

[0116] S1. Preparation of liquid electrolyte

[0117] LiFSI was dissolved in a solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1 to prepare a liquid electrolyte with a concentration of 1 mol / L, and the liquid electrolyte was divided into two parts.

[0118] S2. Preparation of solid electrolyte

[0119] The polymerizable monomer methyl methacrylate and the initiator azobisisobutyronitrile were dissolved in a portion of liquid electrolyte at mass fractions of 5 wt % and 0.2 wt %, respectively, and mechanically stirred at 25° C. for 1 hour to obtain a raw material for forming a solid electrolyte.

[0120] S3. Prepare positive electrode sheet

[0121] Nickel-cobalt-manganese (NCM) ternary material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 97:1:2, N-methylpyrrolidone is added, and the mixture is stirred for 0.5-6 hours to obtain a positive electrode slurry; the mixture is then evenly coated on the positive electrode current collector, dried, cold pressed, and cut to obtain a positive electrode sheet.

[0122] S4. Preparation of negative electrode sheet

[0123] The negative electrode active material, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were added into deionized water in a weight ratio of 97:0.5:1.25:1.25, mixed and stirred for 3 hours to obtain the negative electrode slurry, which was evenly coated on the negative electrode current collector. After drying, cold pressing, and slitting, the negative electrode sheet was obtained.

[0124] S5. Select the isolation film

[0125] Polypropylene film is used as the isolation film.

[0126] S6. Preparation of battery cells

[0127] Following conventional lithium battery assembly processes, a separator is placed between the positive and negative electrodes, wound into a core to create a bare cell. This bare cell is then placed in an aluminum shell, resulting in a hard-shell battery without liquid injection. After the cell is dried, the first liquid injection is performed, injecting the raw materials for forming the solid electrolyte. Once the electrolyte is fully saturated, the cell is heated in a constant-temperature forced-air oven at 70°C for 12 hours to form the solid electrolyte. A second liquid injection is then performed, injecting another portion of liquid electrolyte. After the sealing pins are welded and high-temperature aging is performed, the resulting battery cell is completed.

[0128] Test Example 1

[0129] The cycle performance and mass energy density of the battery cells of Examples 1 to 15 and Comparative Examples 1 to 10 were measured, and the results are shown in Table 2.

[0130] The 80% SOH cycle number is tested by the following method:

[0131] Place the battery cell in a constant temperature environment and program the following: let it rest for 10 minutes, charge at 0.33C to 4.25V, then charge at constant voltage until the current drops to 0.05C. Then, proceed to the next step, let it rest for 10 minutes, and then discharge at 0.33C to 2.5V. This constitutes one charge-discharge cycle, with the discharge capacity being the first cycle's discharge capacity. Repeat the above cycle for a certain number of cycles until the discharge capacity reaches 80% of the first cycle's discharge capacity. Record the number of charge-discharge cycles for the battery cell.

[0132] The mass energy density is measured by the following method:

[0133] At 25°C, charge to 4.25V at 0.33C, charge to 0.05C at 4.25V constant voltage, let it rest for 10 minutes, and then discharge to 2.5V at 0.33C. Record the discharge capacity and then calculate the mass energy density during discharge:

[0134] Mass energy density (Wh / kg) = discharge capacity (Wh) / battery cell mass (kg).

[0135] Table 2 Performance of battery cells of Examples 1 to 15 and Comparative Examples 1 to 10

[0136] As shown in Examples 1-3, the ratio x of the fully charged thickness of the negative electrode sheet to the uncharged thickness of the negative electrode sheet is 19, the negative electrode active material of the negative electrode sheet is graphite, and the silicon content of the negative electrode active material is 0. When the ratio y of the mass of the solid electrolyte to the mass of the electrolyte satisfies 0 < y ≤ 50%, the battery cell has an 80% SOH cycle number of 2500 cls to 2620 cls, and a mass energy density of 230 Wh / kg to 240 Wh / kg. A comparison of Examples 1-3 and Comparative Examples 1-2 shows that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte satisfies y > 50%, the battery cell has an 80% SOH cycle number of only 900 cls to 1200 cls. In other words, when the battery cell experiences a water drop and the volume expansion rate of the negative electrode sheet is low, excessive solid electrolyte lock-in is not required, as excessive solid electrolyte only increases polarization.

[0137] From Examples 4 to 6, it can be seen that the ratio x of the fully charged thickness of the negative electrode plate to the uncharged thickness of the negative electrode plate is 28, the negative electrode active material of the negative electrode plate is a mixture of graphite and silicon-based materials, and the silicon content in the negative electrode active material is 5 wt%. When the ratio y of the mass of the solid electrolyte to the mass of the electrolyte in the electrolyte satisfies 50% < y < 90%, the 80% SOH cycle number of the battery cell is 1700cls~1750cls, and the mass energy density is 255Wh / kg~260Wh / kg; from the comparison of Examples 4 to 6 and Comparative Example 3, it can be seen that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte in the electrolyte satisfies y≤50%, the 80% SOH cycle number of the battery cell is only 1550cls, that is, the amount of solid electrolyte is small, and the volume expansion of the negative electrode plate causes more liquid electrolyte to be squeezed out, which has the risk of cycle diving; from the comparison of Examples 4 to 6 and Comparative Example 4, it can be seen that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte in the electrolyte satisfies y≥90%, the mass energy density of the battery cell is only 240Wh / kg, and excessive solid electrolyte will affect the lithium ion transmission rate.

[0138] From Examples 7 to 9, it can be seen that the ratio x of the fully charged thickness of the negative electrode plate to the uncharged thickness of the negative electrode plate is 68, the negative electrode active material of the negative electrode plate is a mixture of graphite and silicon-based materials, and the silicon content in the negative electrode active material is 30 wt%. When the ratio y of the mass of the solid electrolyte to the mass of the electrolyte in the electrolyte satisfies 50% < y < 90%, the 80% SOH cycle number of the battery cell is 1200cls~1260cls, and the mass energy density is 296Wh / kg~302Wh / kg; from the comparison of Examples 7 to 9 and Comparative Example 5, it can be seen that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte in the electrolyte satisfies y≤50%, the 80% SOH cycle number of the battery cell is only 1050cls, that is, the amount of solid electrolyte is small, and the volume expansion of the negative electrode plate causes more liquid electrolyte to be squeezed out, which has the risk of cycle jump; from the comparison of Examples 7 to 9 and Comparative Example 6, it can be seen that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte in the electrolyte satisfies y≥90%, the mass energy density of the battery cell is only 280Wh / kg, and excessive solid electrolyte will affect the lithium ion transmission rate.

[0139] As shown in Examples 10-12, the ratio x of the fully charged thickness of the negative electrode plate to the uncharged thickness of the negative electrode plate is 80. The negative electrode active material of the negative electrode plate is a mixture of graphite and silicon-based materials, and the silicon content in the negative electrode active material is 55 wt%. When the ratio y of the mass of the solid electrolyte to the mass of the electrolyte satisfies 90%≤y≤96%, the battery cell has an 80% SOH cycle number of 780 cls to 820 cls and a mass energy density of 324 Wh / kg to 326 Wh / kg. A comparison of Examples 10-12 with Comparative Examples 7-8 shows that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte satisfies y<90%, the battery cell has an 80% SOH cycle number of only 700 cls, indicating that the amount of solid electrolyte is small, and the volume expansion of the negative electrode plate results in a large amount of liquid electrolyte being squeezed out.

[0140] As shown in Examples 13-15, the ratio x of the fully charged thickness of the negative electrode plate to the uncharged thickness of the negative electrode plate is 90. The negative electrode active material of the negative electrode plate is a mixture of graphite and silicon-based materials, and the silicon content in the negative electrode active material is 60 wt%. When the ratio y of the mass of the solid electrolyte to the mass of the electrolyte satisfies 90%≤y≤96%, the battery cell has an 80% SOH cycle number of 700 cls to 730 cls and a mass energy density of 332 Wh / kg to 335 Wh / kg. A comparison of Examples 13-15 with Comparative Examples 9-10 shows that when the ratio y of the mass of the solid electrolyte to the mass of the electrolyte satisfies y<90%, the battery cell has an 80% SOH cycle number of only 600 cls to 620 cls, indicating that the amount of solid electrolyte is small, and the volume expansion of the negative electrode plate causes a large amount of liquid electrolyte to be squeezed out.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, wherein: The battery cell comprises: a negative electrode plate and an electrolyte, wherein the electrolyte comprises a solid electrolyte and a liquid electrolyte; The ratio of the fully charged thickness of the negative electrode plate to the uncharged thickness of the negative electrode plate is x, and the ratio of the mass of the solid electrolyte in the electrolyte to the mass of the electrolyte is y; When x≤20%, 0<y≤50%; When 20%<x<80%, 50%<y<90%; When x≥80%, 90%≤y≤96%.

2. The battery cell according to claim 1, wherein: When x≤20%, 0<y≤10%; When 20%<x<80%, 70%≤y<90%; When x≥80%, 90%≤y≤93%.

3. The battery cell according to claim 1 or 2, wherein: The solid electrolyte is a heat-curable electrolyte.

4. The battery cell according to claim 3, wherein: The curing temperature of the heat-curable electrolyte is 50°C to 110°C.

5. The battery cell according to any one of claims 1 to 4, wherein: The liquid electrolyte includes a lithium salt and / or a sodium salt, and the lithium salt includes any one or more of LiPF6, LiClO4, LiTFSI, LiFSI, LiBOB, LiDFOB and LiNO3.

6. A method for preparing a battery monomer according to any one of claims 1 to 5, wherein: The method for preparing the battery cell comprises: preparing an electrode assembly; The electrode assembly is placed in a shell, and raw materials for forming the solid electrolyte are injected into the shell to solidify the raw materials for the solid electrolyte to form the solid electrolyte. The liquid electrolyte is then injected into the shell containing the electrode assembly and sealed.

7. The method for preparing a battery monomer according to claim 6, wherein: The solid electrolyte is a heatable solidifying electrolyte. After the raw materials of the heatable solidifying electrolyte are injected into the shell containing the electrode assembly, the raw materials of the heatable solidifying electrolyte are reacted at 50° C. to 110° C. for 3 h to 24 h to form the solid electrolyte.

8. The method for preparing a battery monomer according to claim 7, wherein: The raw materials of the heat-curable electrolyte include a liquid electrolyte, a polymerizable monomer and an initiator.

9. The method for preparing a battery monomer according to claim 8, wherein: In the raw material, the mass fraction of the polymerization monomer is 0.5wt% to 6.5wt%.

10. The method for preparing a battery monomer according to claim 8 or 9, wherein: In the raw materials, the mass fraction of the initiator is 0.1wt% to 0.5wt%.

11. The method for preparing a battery monomer according to any one of claims 8 to 10, wherein: The polymerizable monomer has an unsaturated double bond.

12. The method for preparing a battery monomer according to any one of claims 8 to 11, wherein: The polymerizable monomers include any one or more of ester monomers, carbonate monomers, sulfone monomers, isocyanates, amide monomers, nitrile monomers and fluorinated monomers.

13. The battery cell according to any one of claims 8 to 12, wherein: The initiator includes any one or more of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptylnitrile, azoisobutylcyanoformamide, azobiscyclohexylcarbonitrile, dimethyl azobisisobutyrate, azobisisobutylamidine hydrochloride, azobisisopropylimidazoline hydrochloride and azobiscyanovaleric acid.

14. A battery, wherein: The battery comprises the battery cell according to any one of claims 1 to 5.

15. An electrical device, wherein: The electrical device comprises the battery cell according to claims 1 to 5 or the battery according to claim 14, and the battery cell or the battery is used to provide electrical energy.

Images